Method and apparatus for concentration of ores



April 30, 1963 M. KRAUT 3,087,519

METHOD AND APPARATUS FOR CONCENTRATION OF ORES Filed Nov. 27, 1959 7Sheets-Sheet 1 INVENTOR; MA X KRA U T M. KRAUT 3,087,619

METHOD AND APPARATUS FOR CONCENTRATION OF ORES 7 Sheets-Sheet 2 M 0 m R.A v .n RI A 0 Y l a: w m m %w u l l I 1| m WT M l m w. w a E w m z W v iI n M 0 v 7- k M w n m n n t m "FIFE u ..I\M A E w W A #m a m v Z o "M ZI l! w WG- II. I Pyl hu w w J I ll v q E E 8 it 6 1 April 30 1963 FiledNov 27, 1959 April 30, 1963 Filed Nov. 27, 1959 M. KRAUT METHCD ANDAPPARATUS FOR CONCENTRATION OF ORES 7 Sheets-Sheet 3 April 30, 1963 M.KRAUT METHOD AND APPARATUS FOR CONCENTRATION OF ORES Filed Nov. 2'7,1959 7 Sheet 5 4 VENTOR I ATTORNEY April 30, 1963 M. KRAUT 3,0

METHOD AND APPARATUS FOR CONCENTRATION OF ORES Filed Nov. 2'7, 1959 '7Sheets-Sheet 5 INVENTOR 4/41 AZ PAWT ATTORNEYJ M. KRAUT 3,087,619

METHOD AND APPARATUS FOR CONCENTRATION OF ORES April 30, 1963 '7Sheets-Sheet 6 Filed NOV. 27, 1959 IHHHIH ATTORNEYS April 30, 1963 M.KRAUT 3,087,619

METHOD AND APPARATUS FOR CONCENTRATION OF ORES Filed Nov. 2'7, 1959 '7Sheets-Sheet 7 United States Patent 3,087,619 METHOD AND APPARATUS FORCONCEN- TRATION 0F ORES Max Kraut, San Francisco, Calif., assignor toWestern Machinery Company, San Francisco, Calif., a corporation of UtahFiled Nov. 27, 1959, Scr. No. 855,597 27 Claims. (Cl. 209-456) Thepresent invention relates to improvements inmethods of an apparatus forseparating fine mineral particles of a high density from fine particlesof lower density'in a fluid or liquid medium. The present invention isof particular utility in the separation of suspensoids which as the termis herein used are particles which are too fine to settle in a specificmedium within a practical time limit allowable under operatingconditions.-

This application is a continuation in part of my copending applicationSerial No. 674,266, filed July 15, 1957, which was a continuation inpart of my application Serial No. 601,924, filed August 3, 1956, bothnow abandoned. 7

Conventional methods such as jigging and apparatus for performing thesemethods have no effect on suspensoids and can not effect theirseparation. Jigging and other similar methods can only effect separationon relatively coarse particles by stratification, wherein the particlesreadily settle in a pulsating medium with the heavier particlesdisplacing lighter particles by gravity. 7

Examples of prior devices and methods are disclosed in United StatesPatents No. 2,242,020, issued May 13, 1941, to Wood, for ConcentratingCell; No. 2,271,650, issued February 3, 1942, to Kraut, for Jig; No.2,523,364, issued September 26, 1950, to Glover, for Ore ConcentratingJig; No. 2,570,035, issued October 2, 1951, to Laughlin, for Means ofWet Screen Sizing; No. 2,638,220, issued May 12, 1953, to Schneider, forUnderwater Screening; No. 2,708,032, issued May 10, 1955, to Heyman, forMica Flake Classifying Device and Method; and No. 2,765,911, issuedOctober 9, 1956, to Vissac for Fluidized Pulsating Jig.

In the present invention particles of differing size and density aredischarged at substantially equal velocity into a fluid body. Particlesof equal mass (volumexdensity) will have equal momentum (mass velocity)as they approach the fluid body but the more dense smaller particles,having a smaller exterior surface, will encounter lower resistance tomovement through the fluid and will thus penetrate the fluid body morereadily and deeply than particles of equal mass but lesser density.Particles of equal volume but differing densities when discharged towardthe fluid' body at equal velocities will have differing momentaproportional to their respective densities as they approach the fluidbody so that the more dense particles will have greater power ofpenetration into the fluid body than equal volume particles of lesserdensity and likewise penetrate the fluid body more deeply.

The present invention utilizes these principles by a1- ternatelydischarging a high velocity jet of intermixed particles of varyingvolume and density into a stationary body of fluid of predetermineddensity and viscosity and subsequently imparting a substantially slowercounter movement to the fluid body at a velocity sufficient to overcomethe momentum of the less dense suspended particles. In this manner themore dense particles continue moving through the fluid body to a firstpoint of removal and the less dense particles are returned toward thejet to a second point of removal. I

The method, according to the present invention, is based on theprinciple of imparting to the particles greater momentum or kineticenergy to overcome the resistance 3,087,619 Patented Apr. 30, 1963 ofthe medium (viscosity resistance) whereby particles of equal diameterbut of greaterdensity acquire greater energy than lighter particles andthereby have greater penetrating power in the medium. Applying thisprinciple toa slurry carrying suspensoids by injecting the slurry athigh velocity into a vessel carrying a liquid medium, particles withgreater kinetic energy will penetrate the medium to greater depth thanparticles with lesser energy. Small particles of greater density mayacquire equal momentum with larger particles of lesser density, but inthat case the larger particles meet a larger viscosity resistance due totheir larger surface which lessens their penetrating power. A countercurrent applied to the medium will readily carry back or reverse thedirection of motion of particles of lighter density and greater surfacearea. The combined alternate action of jet and reversing counter currenteffect a positive separation of the heavier from the lightersusp'ensoids within certain size limits and thereby elfect the desiredconcentration of suspensoids of greater density. These suspensoids ofgreater density are usually mineral particles which are recovered forfurther processing.

The following description of the present invention will proceed firstwith a description of several jigs constructed in accord with andutilizing the method of the present invention and then with adescription of the utilization of the present method in other apparatusto illustrate the broad applicability of the principles of the presentinvention.

Briefly described, the apparatus and the method, as employed in jigs,are such to impart alternately and successively to the mass of the pulpor slurry induced relatively slow upward movements through a suitablesupporting screen having floatable objects thereon of substantially thesame specific gravity as the slurry followed by an induced greatlyaccelerated downward movement through the screen. The objects,preferably balls, rise with upward fluid movement to open the screenorifices and fallto partially close the screen orifices on the highvelocity downward fluid movement. The downward movement of the fluidbelow the screen and the orifice restricting movement of the objects issufliciently rapid that a vacuum suction space is created under thescreen and a high pressure differential between the top or the fluidabove the screen and the underside of the screen which provides a largenumber of high velocity downward jets discharging into the fluid bodybeneath the screen. The high velocity of the slurry in the downward jetsimparts to the suspended particles therein high kinetic energies ormomenta in proportion to their respective masses. Relatively largegangue particles of low density acquire equally high kinetic energy andmomentum as fine equal mass mineral particles of high density, but dueto their larger volume and exposed surface area encounter greaterresistance to movement through the fluid body into which the aredischarged than more dense particles of equal mass. Likewise, as betweenthe particles having equal volume, high density particles will havehigher kinetic energy and momentum and can penetrate the fluid bodybeneath the screen more readily and can overcome the resisting upwardslow currents of slurry and water heneath the screen and continue ontheir downward path, whereas having lesser kinetic energy and momentumof the less dense small ganglle particles will be overcome and the lessdense particles will be carried along with the up ward current of slurryand water through the screen.

If the kinetic energy of any coarse low density gangue particles is notcompletely overcome by the upward movement of the fluid body through thescreen, then in a second step of treatment, such as any well-knownjigging or tabling operation, the relatively coarse or large gangueparticles of low density which are recovered together with the finemineral particles of high density can be readily separated from eachother, resulting in a relatively high grade final concentrate of thefine mineral particles.

For definition purposes it is to be understood that the method step ofscreening and the structure which, for lack of a more descriptive term,is referred to herein as a screen, does not contemplate .a screen memberhaving openings or mesh which separates components of the slurry by flowtherethrough, but rather contemplates openings in the screen which aresufiiciently large at all times to permit passage therethrough in eitherdirection of all component particles of the slurry, the separation beingaccomplished by the relatively slow upward movement of the slurrythrough relatively large orifices followed by relatively fast downwardmovement through orifices which have been reduced in size, the downwardmovement including inducing a vacuum below the screen.

Exemplified forms in which a suitable apparatus and method of theinvention may be embodied are described herein, the apparatus of theinvention being illustrated in the accompanying drawings which are madea part hereof, and the method being also described by reference to saiddrawings:

In the drawings:

FIGURE 1 is a vertical transversely central view in section of theapparatus of the invention, on line 11 in FIGURE 2;

FIGURE la is an enlarged fragmentary section taken substantially alonglines 1a1a of FIGURE 1;

FIGURE 2 is a horizontal transverse view on line 22 of FIGURE 1;

FIGURE 3 is an enlarged fragmentary longitudinally transverse detailedview of a portion of FIGURE 1;

FIGURE 4 is an enlarged fragmentary laterally transverse detailed viewof a portion of FIGURE 1;

FIGURE 5 is an enlarged fragmentary plan view of a portion of FIGURE 1,the view being partly broken away;

FIGURE 6 is an enlarged fragmentary vertical section of a portion oftank and supporting screen or grille shown in FIGURE 1;

FIGURE 7 is an enlarged fragmentary plan view of a modified form ofsupporting screen or grille means;

FIGURE 8 is an enlarged fragmentary centrally transverse verticalsection of another modified, and preferred, form of supporting screenunit, including portions of the tank structure;

FIGURE 9 is a fragmentary plan View of a portion of FIGURE 8;

FIGURE 10 is a fragmentary plan view of still another modified form ofsupporting screen structure, reduced in size in relation to FIGURE 6;

FIGURE 11 is a fragmentary transverse vertical section of the screenstructure shown in FIGURE 10;

FIGURE 12 is a vertical cross-section viewed from the front of theapparatus and illustrating a further embodiment according to the presentinvention;

FIGURE 13 is an enlarged fragmentary elevational view substantiallyalong the line 13-13 of FIGURE 12;

FIGURE 14 is an enlarged fragmentary section substantially along theline 1414 of FIGURE 12;

FIGURE 15 is an enlarged fragmentary section along line 15-15 of FIGURE12 more clearly illustrating the pocket grid screen with the pocketrecessed flow retarding balls removed;

FIGURE 16 is a cross-sectional view in elevation similar to FIGURE 12but showi g a modified form for removing the heavier concentrates;

FIGURE 17 is a cross-sectional view in elevation similar to FIGURE 12.but showing another modified form [for removing the small less denseparticles;

FIGURE 18 is a section substantially along line 18-418 of FIGURE 17;

FIGURE 19 is a diagrammatic view illustrating still another embodimentof the present invention.

Referring to the drawings in which like reference characters indicatecorresponding parts in the several views, 10 indicates a supportingframe which is preferably rectangular in plan, at one side of which is asource of power for operating the apparatus, herein illustrated as anysuitable motor generally indicated 11 for providing a differential of arelatively slow upward and a relatively fast downward motion to a hutchof the concentrating apparatus, the motor preferably being of the typeillustrated and described in my United States Letters Patent No.2,766,735, dated October 16, 1956.

Supported upon the upper portion of the frame 10, as at L2, is securelymounted a tank 13 for containing a slurry, illustrated as an open topboxlike receptacle preferably in this embodiment squarely rectangular atits upper portion, though it may equally well be circular in plan ifdesired.

At one port-ion of its peripheral wall adjacent the up- .per edge, thewall of the .tank has an overflow opening 14 adjustably regulated by asuitable gate 15 which may open into any suitable discharge launder (notillustrated).

Suitable feed means are provided for feeding ore pulp into the tankcomprising a feed hopper 16 adjacent the upper edge of the tank, havingsuitable communication with the interior of the tank through feed chute18, the feed opening 17 into the tank being preferably below asupporting screen structure generally indicated 19, to be furtherdescribed.

While in FIG. 1 the feed for the ore pulp is shown below the screen asthe preferred form of the invention, it is to be understood that withcertain types or fineness of ground ore containing no sandy material,the ore pulp may be fed above the supporting screen.

The screen structure is supported in the upper portion of the tank,preferably above the feed opening 17, by a screen-supported channelmember 20 extending around the interior wall of the tank and providing agroove 21 into which the screen structure sits with a suitable packingseal 22. Depending into the tank below the channeled support member 20and extending transversely across the tank there may be a plurality ofrelatively spaced baffle partitions 23.

The lower portion of the tank comprises an inverted frusto-conical wallmember or vessel 24 having a relatively arge opening 25 at its bottomwhich, in turn, is closed by an inverted conical hutch 26 having sealedcona flexible diaphragm 27, such as rubber, by means of which the hutchmay be vertically reciprocated relative to said opening 25 of theconical lower wall of the tank, manifestly to provide said upward anddownward movements of the slurry. At the vertex of its cone the hutchhas an outlet opening 28 to which is connected a valve member 28a, to befurther described.

The supporting screen structure 19 which is mounted within the upperportion of tank 13 comprises a peripheral supporting side wall 29fitting conveniently and slidably removably within the tank wall, thelower edge of said side wall of the screen structure resting in thegroove 21 and being sealed by the rubber packing 22.

The supporting screen may be any suitable mechanical form which mayeffectively provide for carrying out the invention, severalmodifications thereof being exemplified herein. In FIGS. 1 to 6 thescreen structure comprises screen-supporting bars 30 and 31 mountedtransversely within the confines of the side wall 29, being suitablysupported at ends, as by a bracket 33 connected to the side wall. Thesupport bars 30, 31 are preferably in pairs in which the bars in eachpair have overlying relation, the opposed faces of the bars in each pairbeing spaced and mounting between the opposed faces thereof a suitablesupporting screen member 34 which may be made of relatively spacedparallel slats 35, providing openings or orifices 35a, therebetween, theslats being exemplified as spaced apart substantially 6 mm. (about 7inch). Suitable supporting cross bars or .tie members 36 may also beemployed to support and maintain the spacing of the screen slats. Thelower tier 30 of the support bars may be fixedly welded in place as at37 and preferably the upper tier is removable for cleaning orreplacement of the screen slats 35.

On the upper face of the screen slats 35 are loosely deposited aplurality of small objects of relatively light weight and susceptible toup and down movement with the pulsations or movements of the slurry.Such objects in order not to pass through the screen, manifestly shouldbe of slightly greater diameter than the spacing or slot openings 3511between the slats 35, and they should have a slightly, almost minutely,greater specific gravity than the slurry, so that such objects and theslurry are substantially in balance by the same order of specificgravity, whereby such objects may be raised with the slightest upwardmovement of the slurry through the screen. As an example, if the slurrybe of the order of 1J1 the specific gravity of such objects may be 1.2.An example of such objects may be cited as polyethylene or vinyl pelletsor balls 39, the diameter or which may, for example, be 7 mm. if theslots 35:: between the screen bars are 6 mm. A suflicient number ofthese balls are placed upon the screen openings to provide a planethereof illustrated herein as one ball deep. In FIGS. 1 to 6, the ballsare closely spaced, to be substantially in relative contact at theopposed portions of their circumferential faces, and provide a layer ofballs which may rise with the upward movement of the slurry to providerelatively large screen openings, and tall with the downward movement ofthe slurry body, whereby, when they are levelled out upon the screenopenings, they provide orifices 39a of reduced size through whichinduced accelerated high velocity downward jets of slurry may flow. Anexample of such reduced area of opening may be one-third to one-fourthof the area of the Ifiull opening. Because of the slow up ward movementof the slurry, they are not excessively displaced, though, as aprecaution against such displacements, any suitable guide means may beprovided for the balls in their said movements. The screen and ballsthereon may best be described as a floating check valve portion of thescreen with return by-pass of slurry as downward jets through thereduced orifices 39a. As a further precaution against suchupwardmovement of the balls to an extent that they might be permanentlycarried out of the screen structure and be discharged at outlet 14, aretaining guard screen 38 of a mesh that will not pass the balls may beplaced over the compartments in which the .balls operate, a 6 mm. screenbeing satisfactory for this purpose if the balls are 7 mm.

The density of the slurry is determined by the relative contents ofsolids, sands and slime in water. Therefore, means are provided forintroducing water into the slurry for the purpose of independentlyregulating its density and controlling the quantity of water which maybe introduccd, such regulation and control preferably being at oradjacent to the annular opening 25 of the conical portion 24 adjacent tothe diaphragm 27. Such a means is herein exemplified by conduit pipe 45which cornmunicates at its upper end with a source of water supply 46through an elbow 47. The conduit pipe 45 is co-axial with the conicalvessel portion 24, and at its lower end the conduit passes through theapex of, and thereby comniunicates with, the interior of a hollowconical hood valve 48 which is fixedly mounted thereto as at 49, by asuitable sealing body 51}. Fluid connnunieation between the interior ofpipe 45 and the interior of valve 48 may be established by any suitablepassage means such as a port 48a ("FIGURE-S l and 1a) formed in pipe 45.At the base of its cone the outwardly flared tapered wall of watertherebetween.

ti the conical hood is of a diameter substantially similar to thediameter of the opening 2 5 so as to snugly fit said opening forselectively and adjustably opening and closing said opening, as shown bybroken lines in FIG. 1. For purposes to be described, the conical hood48 may have a ring 51 internally adjacent to its base edge.

At its opposite or upper end the water conduit 45 has an adjustmentmeans whereby it may be raised and lowered and thereby raising orlowering the hood 48 and thus selectively determining the area ofannular opening between the base edge of hood 48 and the wall of opening25 whereby the quantity of water flowing into the lower portion of theconical vessel at the opening 25 may be controlled and adjusted relativeto the slurry, the means for such adjustment comprising a rotatable handwheel 52 at the upper end of the water conduit which may be supported ona cross bar 53 at the top of the tank. If desired, a tubular sleeve 54may enclose said water conduit and extend from the under side of saidcross bar to the upper face of screen structure 19. Since the waterconduit is vertically adjustable, manifestly, it has a sliding relationin such a sleeve. 7

Means for regulating the quantity of water discharged into the slurryincludes a secondary hood valve 55 within the hood valve 48. Preferablyit is also conical con- ;Eorming generally to the form of the interiorof the conical hood 48, with relation to which it is spaced, and oflesser diameter at its base, providing for a flow of This secondary hoodvalve 55 is mounted at the lower end of a control rod 57 which ismounted longitudinally through the conduit 45, the lower end of the rodbeing stabilized at the vertical axis of the cone 4 8 by a bracket 58transversely of the opening 25 of the conical vessel 24, the rod '57extending through and beyond the opposite upper end of the conduit 45:whereat it is longitudinally adjustable by a threadedly mounted handwheel 59 to raise and lower the secondary hood valve. The baseperipheral edge of this secondary hood valve thus opens and closesrelative to the annular ring 5-1 of the conical hood and therebyregulates the quantity of the flow of water into the slurry.

Valve 28a mounted at the outlet opening 28 of the hutch 26 preferably isan upwardly retroverted goose-neck tube 60 communicating with saidoutlet opening 28, and having a check valve 61 therein which opens uponthe .upward movements of the hutch to permit outward flow through thetube and closes against reverse or backflow into the hutch upon thedownward suction stroke of the hutch, since it is undesirable to haveair drawn into the hutch on the downward or suction stroke which createsa vacuum suction under the screen,

Since the structure and operation of .the apparatus contemplates avertical reciprocation of the hutch relative to conical member 24, byflex-ore of the resilient diaphragm 27, means are provided for suchvertical reciprocation of the hutch comprising the prime mover or motor11 which, by suitable connection 65, vertically reciprocates a cross arm66 of a jig yoke having spaced parallel arms 67 which are pivoted atopposite ends as at 68. Transversely between the two pivoted arms 67 ofthe jig yoke is a rocker shaft69 which extends centrally through theinclined conical wall of the hutch with sufficient pivotal action sothat the hutch may be vertically reciprocated on its Manifestly thehutch may ride up and down with the rocker shat-t relative to opening 25responsive to the flexure of the resilient diaphragm 2,7 and provideupward and downward movement of the slurry. For conservation of motivepower the jig yoke may be CQUIllIGI'ebfllfiIlCfid ly a3; suitable means,such as the balancing weight and ar The prime mover or motor 11 is, asstated, preferably of the structure disclosed in my aforesaid UnitedStates patent, but Whether of this or other type, it has thecharacteristics of imparting to the hutch a relatively slow upwardmovement followed by a rapid downward movement, the upward movementforcing the slurry mass relatively slowly upwardly toward and throughthe screen, and the rapid downward movement setting up a vacuum suctionbelow the screen, the purpose of which is to be explained in connectionwith the operation of the method which may be carried out by theapparatus as herein described.

In FIG. 7 there is shown a modified form of supporting screen member inwhich a plate 70 has relatively closely spaced circular openings 71 andthrough which the slurry may flow upon the upward and downward movementsthereof, small objects such as cubes 72 larger than the openings 71serving the same purpose and function, relative to the openings in theplate, as the balls 39 in FIGS. 1 to 6 of the drawings, the upwardmovement of the slurry raising the cubes and the downward movementreseating the cubes in the openings and leaving a portion 73 of theopenings free for downward flow of jets of slurry through orifices ofreduced area as previously described.

FIGS. 8 and 9 illustrate a second modified and preferred form of screenstructure. In this modification the screen structure is generallyindicated 80, which includes a peripheral side wall 81, supported in thesealing seat 22 of the tank, and in which the side wall may be ofgreater height than in FIGS. 1 to 6 for purposes to be described. Inthis modification transverse screen supporting bars 82 support atransversely horizontal screen plate 83 comprising a plurality ofside-by-side or juxtaposed downwardly tapered recesses 84 which areexamplified as inverted frusto-pyramidal pockets substantially squarelyrectangular at their open top and having side walls convergingly tapereddownwardly, preferably at an angle of substantially 60 degrees, to asquarely rectangular opening 85 at the bottom. The objects or balls 86have characteristics similar to the balls 39 previously described andhave substantially the same specific gravity as the slurry, andtherefore function in the same manner, rising and falling within therecessed pockets. Each ball is guided within a pocket by the side wallsthereof, the balls being retained in the recessed pockets by anoverlying retaining screen 87 mounted upon the upper face of the screenplate 83, and supported upon the upper edge of the tapered walls. It mayagain be pointed out by way of example that if the balls 86 are of 7 mm.diameter the rectangular opening 85, at the bottom of the recessedpockets, as Well as the mesh of the retaining screen 87, may be 6 mm.Upon relatively slow upward movement of the slurry the balls rise toprovide relatively large open orifices of the lower screen openings 85and fall with the vacuum-induced relatively fast downward movement ofthe slurry, eifectively reducing the fluid flow area of the rectangularscreen openings 85, and providing the orifices 85a of reduced open areathrough which high velocity vacuum-induced jets of slurry are projecteddownwardly upon the downward movement of the hutch, as indicated by thebroken lines in FIGURE 9 showing the seating area of the balls relativeto the rectangular openings 85.

The screen structure may be further modified by a deposit of arelatively thick layer 88 of loosely and miscellaneously disposedobjects on the upper face of the retaining screen 87, a layer thicknessof six inches being stated as a practical and efiicient example. Theseloosely disposed objects are preferably polyvinyl cubes havingsubstantially the same specific gravity as the slurry (previously statedas 1.1), and dimensioned in size so as to be suporpted above theretaining screen 87, that is, substantially 7 mm. if the retainingscreen is 6 mm. mesh. The inclusion of the layer 83 may make itdesirable to appropriately increase the height of the side Wall of thescreen structure and correspondingly raise the overflow discharge outlet14. A grill 89 may be mounted across said overflow discharge outlet toprevent the objects or Q cubes 88 from being carried out of the tankwith the overflow waste slurry. It is to be understood that theseloosely disposed particles deposited above the retaining screen may besimilarly employed in relation to all forms of the supporting screensand balls described in the several exemplifications of the supportingscreen structure.

In FIGURES 10 and 11, another modified form of screen is disclosed inwhich there are transverse supporting bars 90 which support aball-supporting screen 91 of relatively spaced screen slots 92triangularly normal in vertical section, providing elongated rectangularorifices 93. Balls 94 in this modified form of screen operate in thesame manner as the balls 39 in FIGURES l to 6 to open the screenorifices 93 upon upward movement of the slurry and partially close saidopenings 93 to provide the reduced openings 93a upon downward movementof the slurry as previously described.

In this modification of FIGURES l0 and 11, the balls are guided in suchvertical movement in pockets 95 formed by the slot members 92 andvertical partitions 95 upstanding from the screen 91. A retaining screen97 may overlie the supporting screen and balls, and have superimposedthereupon a layer of miscellaneously and loosely disposed objects 98having characteristics as previously described. The guide members orpockets thus provide three vertical Walls substantially perpendicular tothe plane of the screen, and the fourth wall is divergingly inclinedupward and outward at substantially a 30 degree angle, whereby thepockets are downwardly tapered from a relatively large upper open areato a smaller lower area in which the openings 93 are positioned, wherebythe freedom of space for upward movement of the slurry is increased andthe balls 94 are guided to seat rapidly :and accurately in the openings93 responsive to the downward movement of the slurry to provide theorifices 92a of reduced area.

The operation of the method and apparatus may be basically describedwith reference to FIGURES 1 to 6, supplemented by further referencesappropriate to the modifications of the supporting screen structures ofFIG- URES 7 to 11.

In operation, the ore pulp enters the slurry mass in tank 13 asindicated by hopper 16 and the feed opening 17 in the drawing. It ispreferred and is believed to be important for most eflicient operationthat the ore pulp enter the slurry below the supporting screen for thereason that if it is fed above the screen the slow upward current wouldnot maintain the relatively large gangue sand particles in suspensionabove the screen whereupon these rapidly settle, choking the openingsand thus form a matting on the screen, which would prevent the mostefficient functioning of the method and apparatus. By feeding the orepulp below the supporting screen structure 19 these larger gangue sandssettle downwardly in the slurry toward the bottom of the vessel 24.

With the slow upward current of the slurry, the light layer of balls orspheres on top of the screen openings, being substantially the samespecific gravity as the slurry, are raised thus opening the full area ofthe orifices of the entire screen free for the rising current of theslurry to pass at a slow upward velocity through said openings. The slowupward motion of the slurry through the fullsized screen openingscarries in suspension the fine and light gangue particles together withfine mineral particles of high specific gravity, but not the sands oflarger gangue particles. By successively repeated slow upwardpulsations, the slimes and the fine light gangue particles graduallywork to the upper stratum of the slurry above the screen and aredischarged in the overflow at outlet 14. The slow upward current of theslurry is, however, insuflicient to carry with the current to said wasteoverflow the fine mineral particles, since, because of their highspecific gravity, they do not flow upwardly as readily as the slirnesand fine gangue and, secondly, because the upward motion imparted to theslurry through the full 9 openings of the screen is followed by anaccelerated very rapid downward motion through screen openings ofreduced size responsive to a vacuum suction below the screen, as will befurther described.

On the following rapid downstroke of the hutch, responsive to the motoras aforesaid, the hutch drops quickly and with it the pulp level beneaththe screen, which causes a downward vacuum suction under the screen. Theballs on top of the screen openings. settle rapidly responsive to thevacuum suction, whereby the balls close the screen openings only partly,leaving a large number of small openings 39a between the balls andthrough the screen, whereby high velocity jets of the slurry are inducedthrough these small openings by the high differential pressure acrosssuch openings between the top and bottom of the screen due to the vacuumsuction under the screen and the weight of the slurry trapped above thescreen augmented by atmospheric pressure. These jets carry with them themineral particles which are thus invested with high kinetic energy. Thejets, upon striking the slurry level below the screen, are resisted bythe next succeeding up-current of slurry and hutch water, permittingonly particles with high kinetic energy to continue downward against theslowly rising current. The preconcentrate thus for-med below the screenis a composite of the fine mineral particles of high specific gravityand the relatively large gangue particles of lower specific gravity. Thesmaller and lighter gangue particles and the slimes with low kineticenergy and relatively small surface area are carried along with therising current of the pulp through the screen and eventually aredischarged over the discharge tailings lip 14.

The preconcentra-tes, in successive cycles of pulsations continue towork down into the hutch and are discharged from the bottom of theconical hutch through the automatic valve 28a which opens on the upwardor pressure stroke of the hutch and closes on the downstroke or suctionstroke of the hutch and thus prevents an intake of air which may destroythe vacuum and would have a deleterious effect on the operation of themethod. The velocity of the current in the annular space around thecircumferential base of the hood 48 is regulated and controlled by theposition of said conical hollow hood relative to the circumference ofopening '25, and the quantity of hutch water admitted is controlled bythe hollow cone valve 55 within said hood, thereby affecting the gradeof concentrates of the slurry being processed.

Having described the method of operation in relation to the structuresshown in FIGURES l to 6, the modified screen structures shown in FIGURES8 to 11, provide for guiding of the balls in the upward and downwardmovement thereof, which is especially advantageous in relatively fastoperation of the method. In other respects the operation is the same.

Referring to the layer of objects or cubes 88, as shown in FIGURES 8 and9, this ancillary miscellaneously and loosely disposed layer of objectsmay be employed above the retaining screen with any or all of the formsof ballsupporting screens illustrated and described. The phenomenaeffected by such layer is to more completely separate the fine mineralparticles from the slimes and fine gangue particles in the slurry thatpasses upwardly through the ball-supporting screen. The said objectsabove the retaining screen, being relatively light in weight and of thesame order of specific gravity as the slurry, rise and fall with therespective slow upward and fast downward movements of the slurry, andbecause of their miscellaneous positioning they do not obstruct thenormal currents of such flow. The employment of such layer above theretaining screen has an appreciable effect of maintaining the finemineral particles of high specific gravity at r the lower level of thebody of slurry above the ball-supporting screen, but permitting thelighter slimes and gangue to rise to the discharge level. In actualoperation, the inclusion of such an ancillary layer above the sup- Itporting screen unit has increased the overflow of slime waste by twentypercent, and correspondingly decreased the content of slimes and finegangue particles in the preconcentrate drawn off from the hutch.

The velocity of the slurry operative over the entire screen area is afunction of the volume of the feed intake of the slurry and the quantityof the hutch water added.

The preconcentr-ates discharged at the outlet valve 28a consisting ofrelatively coarse gangue particles and fine mineral particles are thenreadily separated from each other by any well-known jigging or tablingoperation whereby there is produced a final relatively high gradeconcentrate of fine mineral particles.

The recovery of fine mineral particles may be further promoted by takingadvantage of mass action by adding to the ore slurry in the tank *aquantity of finely ground material of high specific gravity, such asferro-silioon, magnetite, metallic iron, which may then be readilyseparated magnetically or by gravity concentration from the concentratesand returned to the tank feed in a closed circuit.

By way of example of operation and not as a limitation, the timing ofthe relative up and down movements imparted to the slurry may be of aratio of 40 or 50 to 1, such as an upward movement of four to fiveseconds and a downward movement of one-tenth :of a second, the desirablenumber of such two-Way strokes per minute depending on the fineness ofthe material of the ground ore, which may make it desirable to vary thelength of the stroke and the number of such strokes between ten andsixty per minute.

By way of fiurther explanation of the operation of the exemplifiedsupporting screens and the balls thereon it will be noted that the modeof operation is closely akin to a plate having perforated therein anumber of small swing-check valves corresponding to the number of ballsas herein exemplified, each of such valves having a relatively smalreturn by-pass operating in the same manner as the relatively smallorifices 39a between the balls exemplified herein, whereby the slowupward movement of the slurry would open the entire valve for arelatively free flow therethrough and the accelerated downward movement,which creates a partial vacuum under the screen, as previouslyexplained, would close the valve and provide the downward jets of highvelocity through the small return by-pass orifices.

The recovery of fine mineral particles further may be economicallypromoted by improving the apparatus above described to eliminatepreliminary sizing of the feed.

In the past, it has been the custom to first treat differ- I ent sizesof mineral and gangue particles in separate jigs to facilitate a moreefficient subsequent separation of fine mineral particles of highdensity from its fine less dense gangue particles. In the fine orsu-spensoid size particle ranges particularly treated by the presentinvention, preliminary sizing of the fines to separate large mineral andgangue particles from relatively smaller mineral and gangue particles,is costly and difficult.

Thus, in order to further improve the separation of high densityparticles of small volume from low density particles of varying volumesdensity, a further embodiment of the present invention is illustrated inFIGURES 12 to 15 for obtaining separation of the fine mineral particleshaving high density from relatively low density gangue particles ofvarying volumes over an exceptionally wide range of sizes, therebyobviating, or at least limiting to a large extent, the necessity ofcostly preliminary ore treatments involving fine screening andclassification.

Referring now to FIGURES 12 to 15, and more particularly to FIGURE 12,wherein the further construction embodying the principles of the presentinvention is shown, the reference humeral designates a cylindricalslurry tank open at its ends and fixedly supported upon 11 the upperends of angle iron corner posts 112 of a rigid generally rectangularstructural frame 114.

The bottom end of slurry tank 110 is closed by an inverted conicallyshaped hutch 116 which is coaxially and flexibly attached in fluid tightrelationship to tank 110 by means of a circumferentially extendingdiaphragm 118 made of flexible material such as rubber so as to permitvertical displacement of hutch 116 relative the rigidly supported tank110. At the vortex of its cone, hutch 116 is provided with an outletport 124 which is connected to a downwardly sloping pipeline 126 bymeans of a flexible coupling 128.

The lower end of pipeline 126 terminates in a flared portion 130 rigidlysecured to a closed elevator casing 132 in communication with an opening134 formed in the casing. Casing 132 houses a conventional uprightcontinuous bucket-type elevator 136 having a series of materialreceiving buckets 138 suitably secured to a moving continuous belt 140.At the upper end of elevator casing 132, a material discharge opening142 is provided for emptying the contents of buckets 138.

Referring now to FIGURES 12 and 13, the means for verticallyreciprocating hutch 116 comprises any suitable hydraulic motor 144having fluid inlet and outlet connections 145 and 146 respectively forimparting a differential of a relatively slow upward motion and arelatively fast downward motion to hutch 116. Motor 144 is preferably ofthe type illustrated in the embodiment of FIG- URES 1 to 6, being fullydescribed in said United States Letters Patent No. 2,766,735, whereinthe power member 147 is slowly raised by introduction of fluid pressurethrough inlet 145 and allowed to rapidly fall by gravity upon release ofpressure fluid through outlet 146.

Motor 144 is mounted coaxially above slurry tank 110 on a base plate 148rigidly supported on frame 114 by means of a series of inclined an'gleirons 149 secured at their lower outwardly extending ends to frame 114.As best shown in FIGURE 13, the reciprocable power member 147 of motor144 carries at its upper end a cross arm 154 which is connected to andsupports a jig cross arm 156 below motor 144 by means of a series ofcables or rod and nut assemblies 158.

As clearly shown in FIGURE ating shaft 160 slidably extends throughcross arm 156 coaxial with motor 144 and is resiliently suspended fromcross arm 156 for reciprocable movement therewith by means of a coiledcompression spring 164. Compression spring 164 is mounted on top of jigcross arm 156 between two guide covers 166 and 168 in surroundingrelationship to shaft 160. The upper end of shaft 160 extending beyondspring guide cover 168 is threaded and receives a tightening lock nutassembly 170 bearing against the upper face of cover 168 which is urgedupwardly by spring 164.

The lower end of shaft 160 a hub 171 rigidly fixed to hutch of radiallyextending structural brace members 172. The portion of shaft 160extending downwardly beyond hub 1 71 is threaded to receive a tighteningand lock nut assembly 173 which bears against the bottom face of hub 171so as to resiliently suspend hutch 116 and shaft 160 from cross arm 156in the position shown in FIGURE 12.

Also supporting hutch 116 is a series of equiangularly spaced heavy dutyupright coiled compression springs 174 anchored at their respectivebottom ends to frame 114 and aifixed at their upper ends to a rigidhorizontal plate 175 fixedly secured to hutch 116. For a purpose as willhereinafter become apparent, compression springs 174 flexibly supportonly a predetermined par-t of the dead weight of hutch 116.

By this structure, it will be appreciated that hutch 116 is resilientlysuspended from frame 114. When pressure fluid is introduced into motor144 to uniformly and slowly raise power member 147, cross arm 156 iscarried upwardly by movement of cross arm 154 so as to com- 12, anupright jig operslid-ably extends through 116 by means of a series pressspring 164 and raise shaft 160. Since nut assembly 173 bears against hub171 in the lowered or bottom position of shaft 160, verticaldisplacement of shaft 160 in an upward direction slowly lifts hutch 116to Its upper or raised position. When the pressure fluid acting on powermember 147 is released as described in said Letters Patent No.2,766,735, the power member 147 falls rapidly under its own weightcausing cross arm 156 to drop a corresponding distance by gravity. Thesudden release of pressure on spring 164 allows the energy stored in thespring to be released so that it expands and follows cross arm 156 inits downward movement.

The portion of the weight of hutch 116 and its contents not supported byspring 174 now acts to cause the hutch to fall rapidly from its raisedposition, carrying with it shaft 160 which moves against the bias ofspring 164 in its expanded condition. Hutch 116 continues to fall untilspring 164 becomes sufiiciently compressed by the downward movement ofshaft 160 to resiliently support from cross arm 156 the rest of theweight of hutch 116 and its contents not supported by springs 174.

In this manner, the downward movement of hutch 116 is cushioned and thehutch is shocklessly brought to rest in its lowered position withoutsudden or abrupt stopping to thereby preclude the occurrence ofexcessive strains and stresses in the other structural components of theapparatus that would otherwise occur. Since springs 174 only support apredetermined part of the dead weight of hutch 116, the gravitationalforce corresponding to the remainder of the weight of the hutch notsupported by springs 174 overcomes the bias of spring 164 and theatmospheric pressure forces tending to hold the hutch as will beexplained so as to facilitate the requisite rapid downward movement ofthe hutch.

A pipeline 176 for introducing either hutch water or heavy media intohutch 116, extends horizontally through the conical walls of hutch 116and has a fluid outlet port 177 communicating with the interior of thehutch. Supported above outlet port 177 on pipeline 176 is a perforatedinverted conical shaped hood 178 for evenly and uniformly distributingheavy media or water discharged for outlet 177 into the interior ofhutch 116.

The opposed ends of pipeline 176 extending beyond hutch 116 respectivelyare connected to suitable heavy media and water sources (not shown) bymeans of valved pipes 179 and 180.

Supported within the upper portion of slurry tank by a ring 181 securedto tank 110, is a pocketed grid member 182 disposed in a generallyhorizontal plane but having its top face somewhat gradually anduniformly conically sloped downwardly from its peripheral outer edgetoward the center of tank 110. A central opening is formed in gridmember 182 through which shaft extends. Received through the centralopening of grid member 182 and rigidly fixed thereto is a discharge tube184 for discharging coarse gangue particles of light density into hutch116 where they are removed together with the fine mineral particles ofhigh density. With the present embodiment additional jigging treatmentof the particles removed from the bottom of hutch 116 is required toseparate the dense small mineral particles from the large light gangueparticles. Slidably received in tube 184 is a sleeve 185 which isvertically adjustable and held rigid with frame 114 by means of bolts18511. By this construction, sleeve 185 is readily adjustable to controlthe depth of concentrate formed above grid 182.

As best shown in FIGURES 12 and 14, and 15, memher 182 is provided witha series of upstanding projections 186 having inverted cone shaped crosssections to form a series of individual equidistantly spaced side-bysideor juxtaposed downwardly tapered pockets 188 having substantiallysquared bottom openings 191) providing fluid communication between thetop and bottom of the grid and side walls shaped to conform to invertedfrustopyramids so as to be squarely rectangular at their open 13 top.Recessed pockets 188 are substantially identical to the shape ofrecesses 84 described in connection with the screen embodimentillustrated in FIGURES 8 and 9.

Freely received in each pocket 188 is a ball 192 identical to and havingthe same functional characteristics of balls 86 and 39 illustrated inthe previously described embodiments. Balls 192 as hereinbeforedescribed have substantially the same specific gravity as the slurryintroduced into tank 110 and therefore function in the same manner,rising and falling within their individual recessed pockets 188. Eachball 192 is guided into a seated position over bottom opening 190 in itsrecessed pocket by the side walls thereof and are of such diameter withrespect to the dimensions of the pocket opening 190 that they areretained within their pockets to prevent their falling through thepocket openings.

A's hereinbefore described, upon relatively slow upward movement of theslurry introduced into tank 110, the balls 192 rise to providerelatively large open orifices in grid member 182 and fall with thevacuum induced relatively fast downward movement of the slurry in tank110 to seat over the pocket openings 190 and thereby reduce theeffective fluid flow area of these openings, providing orifices with theside walls of the recessed pockets that are of reduced open area andthrough which high velocity vacuum induced jets of slurry are projecteddownwardly upon the downward movement of hutch 116.

A retaining screen 196 supported by grid member 182 and conically shapedto correspond to the conically shaped upper face of grid member 182overlies the pocket recesses and retains balls 192 in their respectivepockets. Retaining screen 196 is held firmly in place over grid member182 by means of structural ring-shaped members 198 and 200 respectivelyurged downwardly in the abutting contact with the upper face of screen196 by bolts 202 and 204 which are secured to frame 114.

The means for introducing feed into slurry tank 110 comprises adownwardly sloping duct 206 positioned above the tank and extendingradially toward the center thereof. Feed duct 206 communicates at itsinner end with a radial opening 208 formed in a sleeve 210 supportedabove retaining screen 196 on frame 114 coaxially with tank 110 and insurrounding concentric spaced apart relationship to jig shaft 160.Between sleeve 210 and jig shaft 160 an inverted conically shaped tube212 is adjustably supported on frame 114 in concentric spacedrelationship to sleeve 210 by means of bolts 214. The lower wide end ofthe conical tube 212 extends downwardly beyond the lower edge of sleeve210 and forms a feed well space 216 with sleeve 210.

Tailings or light low density particles discharged over the peripheraledge of slurry tank 110 are collected in a peripherally sloped launder222 surrounding the tank near the upper edge thereof.

Thus by the means above described for centrally feeding the ore into theslurry tank 110 and peripherally discharging the tailings, surface crosscurrents are minimized so as to permit the fine dense mineral particlesto settle instead of being carried away over the tailings discharged bythe cross currents. The inwardly sloping conical shape of screen 196 andgrid 182 urges the layer of coarse heavy mineral particles towards thecenter discharge 184.

In operation of the above apparatus thus far described, fluctuations inthe rate of ore feed and variations in the character of the feedcorrespondingly affects the density of the slurry in the hutch.Increases in the feed cause corresponding increases in the slurrydensity. Variations in the slurry density have been found to have asubstantial effect upon the separation of particles. To this end, itwill be appreciated that increases in the feed rate tend to increase thedensity of the medium in the slurry tank and a denser medium, whileassisting in the removal of fine gangue particles, resists and decreasesthe settling velocity of the fine heavier mineral particles thereby re-14 tarding the separation of these particles. Similarly, a reduction orinterruption in the rate of feed tends to lower the density of themedium in the slurry tank and a less dense medium will not providesufiicient fluid resistance to keep the fine gangue particles fromsettling with the fine heavier mineral particles.

In order to compensate for variations in the density of the slurrymedium to thereby assure a more uniform and efficient separation ofparticles over a wide range of particle sizes and to prevent seriousmetallurgical losses, a speed control unit 226 is provided for hydraulicor air motor 144 and comprises a rotary valve 228 in motor inlet 145 forcontrolling the admission of pressure air or fluid to hydraulic motor144. Actuation of valve 228 controls the speed at which power member 147is raised from fully lowered position to fully raised position as ismore fully described in said Letters Patent No. 2,766,735. Rigidlysecured to the operating stem 230 of valve 228 is an operating lever 232having a weight 234 attached to the free end thereof so as to bias theoperating stem 230 to valve closed position. Secured transversely tooperating lever 232 intermediate weight 234 and operating stem 230 is anarm 236 which carries at its lower end the inner telescoping member 238of a conventional mercury dash pot 240 having a support base 242 rigidlysecured to frame 114. By this structure, dash pot 240 resists movementof valve operating stem 230 in either direction and weight 234 tends torotate stem 230 toward valve closed position.

With continued reference to FIGURE 12, the linkage for operating thelever 232 comprises a link 244 rigidly secured at one end to springcover 168 and pivotally secured at its opposite end to the lower end ofa generally upright link 246. The upper end of link 246 is pivotallyconnected to the left-hand end of a force multiplying lever 248 which isfulcrumed about a machine screw 250 threadedly secured in frame 114. Atthe opposite righthand end, as viewed from FIGURE 12, lever 248 carriesa mounting block 252 which is adjustably secured to lever 248 by meansof a screw 254. Mounting block 252 is formed with a tapped bore whichthreadedly receives a stud 256 adjustable in height to abuttingly engageoperating arm 232 between valve stem 230 and dash pot cross arm 236.

By means of this construction, the admission of air or hydraulic fluidinto hydraulic motor 144 is regulated by the height to which cover 168and consequently shaft and hutch 116 are raised. As the density of themedium in hutch 116 increases, the force needed to raise the hutch toits normal raised position correspondingly increases. For a given hutchweight, when valve 228 is set in one position to admit pressure fluidinto motor 144 at a predetermined flow rate, the power member 147, andconsequently hutch 116, will be raised in a predetermined period of timecorresponding to the rate at which fluid is being introduced into motor144-. When the density of the slurry increases so as to increase theweight of the slurry in the hutch and valve 228 is held in its samesetting, a longer period of time will be required to raise the hutch toits upper position. As a result, it will be appreciated that the timerequired for raising the hutch will therefore increase withcorresponding increases in the weight of the slurry in the hutch for asingle setting of valve 228.

In raising hutch 116 as hereinbefore described, a resistivecountercurrent of fluid resists the settling of the particles in theslurry so as to urge particles of low density to the surface of theslurry; This resistive countercurrent of the slurry caused by raisinghutch 116 also tends to resist to a lesser extent downward movement ofthe fine high density particles of small volume which are settling inthe slurry for discharge through the hutch outlet 124. Thus when theupward movement of hutch 116 is prolonged, then the resistivecounterforce' tending to restrain the fine high density particles fromsettling. is increased 1.5 in proportion to the length of time that itis required to raise the hutch, thereby tending to make the separation-of the fine dense particles more diflicult.

In accordance with the present invention, springs 174 are fullycompressed when hutch 116 is dropped to its lowered position and areconstructed to support only a predetermined part of the dead weight ofthe hutch when fully compressed. Thus, the loads carried by springs 174in elongated and compressed positions corresponding to raised andlowered positions of the hutch, remain substantially constantirrespective of variations in the weight of the slurry in the hutch.Spring 164 accordingly supports a load equivalent to all of theremaining weight of the hutch and the slurry not supported by springs174. Since the maximum load supported by springs 174 remains constant,variations in the weight of the slurry are therefore taken up by spring164. When the weight of the slurry is increased, the magnitude ofdeflection of spring 164 is also increased to support the additionalweight and when the weight of the slurry is decreased, the magnitude ofdeflection of spring 164 is correspondingly reduced. For example, if thetotal weight of hutch 116 and the slurry is 3000 pounds and the constantload carried by springs 174 when compressed is 2000 pounds, then theremaining 1000 pounds is carried by spring 164. .If the density of theslurry is increased so that the total weight becomes 3300 pounds, theload carried by springs 174 remains constant and the load taken up byspring 164 accordingly increases to 1300 pounds thereby causing afurther increment of compression of spring 164. Thus the magnitude ofdeflection of spring 164 varies correspondingly according to changes inthe weight of the slurry. Since spring cover 168 is subject tovariations in the magnitude of deflection of spring 164 and since theoperating arm 232 is connected through the system of linkage arms 244,246 and 248 to the spring cover 168, then variations in the magnitude ofdeflection of spring 164 are transmitted to valve 228 to control therate of ipre'ssure fluid flow being introduced into motor 144.

Thus, valve 228 is readjusted by speed control unit 226 at the end ofeach stroke of power member 147 and jig shaft 160 in accordance withvariations in the density of the slurry. When the weight of slurry inhutch increases,

operating arm 232 rotates valve stem 230 between positions permitting anoverall increased rate of pressure fluid flow into motor 144. As therate of fluid flow is increased, the added pressure fluid force actingon the power member 147 to compensate for the additional Weight of theslurry in hutch 116 causes power member 147 and consequently hutch 116to again be raised in a changed time period needed to effect efficientseparation of the particles in the slurry.

Similarly, speed control unit 226 functions to decrease the rate offluid flow into motor 144 as the density of the slurry is reduced. Thus,it will be appreciated that the speed control unit 226 controls the rateof pressure fluid flow into motor 144 in response to variations in theweight of the slurry. The time period for raising the hutch cantherefore be changed to a value at which the most eflicient separationof particles occurs irrespective of changes in the density of theslurry.

In order to protect screen 196 which is generally of fine mesh fromrapid wear, a thin layer of lead shot 260 is placed over screen 196 asshown in FIGURE 15. The density of the lead shot is substantiallygreater than that of the slurry so that the lead shot will not bereadily shifted with the pulsations of the slurry caused by the jigaction. The layer of lead shot 260 performs the function of a finescreen.

On top of the lead shot 260, a layer of relatively coarse beddingmaterial 262 is placed. Bedding material 262 is selected to have aboutequal density as the minerals to be recovered.

In operation of the apparatus above described, the feed of mixed sizesenters through opening 208 into the feed well 216. Motor 144 sets inmotion movable hutch 116 with a relatively slow upward stroke followedby a rapid downward stroke causing the pulsations of currents in theslurry which bring about the separation of light particles of lowdensity from small heavier particles of high density. Above bedding 262the slurry becomes stratified on the slow upstroke followed on thedownstroke by the heavier coarse gangue particles displacing lighterparticles thus forming a bed of coarse concentrates of heavier coarseparticles on top of bedding 262 which is the common method ofconcentration in jigging. During this action the slurry containing theneo-suspensoids and very fine high density mineral particles and finegangue particles of low density which do not stratify and cannot beconcentrated above the screen by the jigging operation indicated, aredrawn down through screen 196 and pocket grid 182 in the form of highvelocity jets into the hutch and separation of the fine heavy mineralparticles from the lighter fine gangue particles takes place as fullydescribed in the operation of the previous embodiments. The layer ofcoarse concentrates formed on top of bedding 262 gradually moves withthe pulsations of the slurry toward the center discharge tube 184 withits height adjustment sleeve 185. The movement of the concentratestoward the center is helped by the conical shape of grid 182 and screen196. The discharge of the coarse concentrate into the hutch isprincipally effected by the difl'erential in pressures above and belowgrid 182 as created by the rapid downward motion of the hutch. Trailingsor fine light particles of low density are discharged over theperipheral edge of the tank and collected in peripheral launder 222surrounding the tank.

The separation of gangue particles from fine mineral particles may beeffectually enhanced by the introduction of heavy media into the hutchthrough pipe 176 under the perforated conical hood 178. Heavy media atthe bottom of the hutch promotes cleaning of the concentrates withoutinterfering with free settling of mineral particles at the top .as wouldoccur where heavy media is introduced with the ore due to increasedviscosity.

The discharge of concentrates (gangue in the case of coal) may beeffected and controlled in various manners depending largely on the kindand size of the material. In FIGURE 12 the discharge is illustrated asbeing controlled by means of elevator 136 which provides a widedischarge opening from the hutch and tends to maintain at all times aconstant level in the hutch irrespective of load.

FIGURE 16 illustrates a modified form of concentrate discharge generallyindicated at 270 and basically consisting of an outlet pipe 272 having adownwardly facing sand bleed 274. Pipe 272 is connected to an upwardlysloping duct 275 communicating with an upright overflow duct 276 havinga series of overflow outlets 278 at different elevations.

By this structure, the rate of discharge from hutch 116 is increasedproportionally with respect to the head of the slurry in hutch 116,since as the level of the slurry in hutch 116 increases, the level ofslurry in overflow duct 276 correspondingly increases to communicatewith an increasing number of outlets 278.

In some cases it may be desirable to keep the coarse concentratesseparate from the fine concentrates which later may require a subsequenttreatment such as pelletizing in iron ores. That may be readilyaccomplished by placing a screen 290 underneath discharge tube 184 andconnecting it to separate discharge duct 292 controlled by a rotaryvalve 294 as shown in FIGURE 16. The screen 290 functions to maintainpulsations of the slurry and suction in the tube 184.

When treating fine material by the apparatus described above, a problemis encountered in that the pulsating currents permit fine particles topass through bedding 262, but the bedding will retain the relativelycoarser but light sand particles of the ore which tend to accumulate ontop of the coarse bedding forming a layer of fine sands indicated at300, FIGURE 17. If this layer 300 is allowed to build up and increase inthickness, it eventually fills up to the mouth of feed well 216,preventing the further admission of feed and interfering with the properoperation of the apparatus. In treating fines, the jig motion, ashereinbefore described, must be kept relatively slow and uniform on theupstroke to prevent undue agitation of the slurry which would tend tokeep fine mineral particles in suspension and prevent them from settlingIn order to maintain the slow motion of the upward slurry current it ispreferable to remove the sand layer 300 and thereby maintain theapparatus in continuous operation. To accomplish the removal of sandlayer 300, the side of slurry tank 110 is provided with an opening 302of suitable width and height as best shown in FIGURE 17. Opening 302 iscovered with an inclined shield 304 having closed sides 306 as clearlyshown in FIGURE 18. Shield 304 is positioned adjacent to the peripheraloverflow edge of tank 110 and slopes down into the bedding slightlybelow the level of fine sand layer 300. Slats 308, held by bracket 310,are removable to adjust the height and level of sand overflow. A slide312 is shiftable in a slot 314 formed by bracket 315 to adjust thedischarge overflow 318 between slats 308 and slide 312. With continuedreference to FIGURES 17 and 18, the sand level is shown to be slightlyraised above its normal level. As the level of sand layer 300 increases,the portion under shield 304 is subject to a squeezing action as aresult of the inclination of the shield. By this action, the sand undershield 304 readily builds up and is discharged through opening 318 intolaunder 222. A series of shields 304 may be arranged around the edge ofslurry tank 110 so that the sand level adjusts itself with thepulsations of the jig. In this manner an effectual sand discharge isobtained while maintaining a normal fine sand level.

By the above constructions of FIGURES 12 to 18, exceptionally wideranges of particle sizes can be efiiciently separated to facilitate therecovery of mineral particles without requiring costly preliminaryscreening, classification or sizing operations. This is particularlyaccomplished in accordance with the present invention by means of thecentral feed 206 and peripheral discharge of tailings above thecylindrical tank 110, the maintenance of a slow and uniform upwardmovement of hutch 116 with sufficient speed to keep bedding 262 in fluidcondition and to allow ample time for stratification of coarse particlesabove grid member 182, the provision of bedding 262 to retain thecoarser fraction of less dense particles above grid 182, the provisionof speed control unit 226 to compensate for changes in the density ofthe slurry, and the provision for uniform distribution of the highvelocity fluid jets by means of grid member 182. By this construction,for example, particles ranging in size from approximately /2 inch downto sizes in a micron range can be effectively and efliciently separated.

While the foregoing descriptions have been largely concerned with theelements of the particular apparatus, it is obvious that the inventionis not necessarily restricted thereto and that functional equivalentsmay be employed to carry out the method of particle separation. Forexample, different screens and motors for operating the hutch may beused.

To illustrate the broad applicability of the method of the presentinvention and to more clearly distinguish the action from known methodsof jigging, a further embodiment is illustrated in FIGURE 19 wherein thereciprocal movement of structural parts that is representative ofjigging methods is not present.

Refrering now to FIGURE 19, a slurry supply tank 330 is connected to asuitable feed pump 332 by means of a duct 334. Pump 332 is provided witha pressure outlet 335 connected by a duct 336 to a stationary pressurechamber 338 rigidly supported by any suitable means (not shown).Pressure chamber 338 is formed with a generally horizontal bottom wall340 having a series of downwardly extending uniformly spaced orifices342 and closed side walls 343. Disposed in spaced relationship beneathbottom wall 340 is a stationary receiving tank 346 rigidly supported byany suitable framework (not shown) and having an upper cylindrical wallportion 348 open at the top and closed at the bottom by a lower invertedconically shaped wall portion 350 rigidly secured to cylindrical wall348 around the bottom peripheral edge thereof. At the vertex of wallportion 350a valved fluid outlet 352 is provided to permit discharge offluid and particles from tank 346.

Adjacent to the bottom edge of cylindrical wall portion 348 is secured acircular generally horizontal plate 353 interfitting with tank 346 andhaving a series of uniformly spaced openings 354.

A peripheral lip 356 is secured to tank 346 adjacent the upper edgethereof to facilitate removal of fluid and particles overflowing thetank.

In order to supply fluid to tank 346 such as water or heavy media, astorage tank 358 is provided for and is connected to tank 346 by meansof a duct 360. Duct 360 communicates with an opening 362 formed in tank346 beneath plate 353.

The means for controlling the flow of fluid through ducts 336 and 360comprises valves 362 and 364 respectively. Valves 362 and 364 aremechanically interlocked as by arm 366 so their operation issimultaneous. As shown in FIGURE 19, movement of arm 366 upwardly opensvalve 362 and concomitantly closes valve 364. correspondingly, movementof arm 366 downwardly opens valve 364 and closes valve 362.

By this construction, it will be appreciated that with the exceptions ofvalves 362 and 364 and pump 332, the apparatus basically has norelatively movable parts for facilitating the separation of intermixedparticles in the feed as will now be described.

Thus, in operation, tank 346 is filled with water or heavy media fromtank 358. The slurry containing the intermixed suspensoids to beseparated is stored in tank 330 and is pumped from tank 330 to pressurechamber 338 by pump 332 to fill chamber 338 with slurry under pressure.The slurry in pressure chamber 338 is discharged downwardly throughorifices 342 in high velocity jets into the medium in tank 346.

Since equal velocities are imparted to the intermixed particles in thejets, those particles of equal mass will acquire equal momentum(massxvelocity) or kinetic energy. Small particles of greater densityacquire equal momentum with larger particles of lesser density but thelarger particles of lesser density owing to their relatively largersurface, meet with a greater viscosity resistance as they enter thefluid in tank 346 in comparison to the smaller particles of greaterdensity. Thus for particles of equal mass and momentum, the smallerparticles of greater density have a greater penetrating power than thelarger particles of lighter density.

Small particles of equal volume but of differing densities acquiredifferent momentums upon being discharged in the high velocity jets.Consequently, the particles of greater density have greater penetratingpower than the particles of equal volume but of lesser density.

By reversing the position of valves 362 and 364 so as to open valve 364and close valve 362, the high velocity jet flow from the pressurechamber is interrupted and water or heavy media is introduced into tank346 adjacent the bottom thereof at a flow rate to provide for a slowupward current in the medium in tank 346 which is uniformly distributedby passage through plate openings 354. This slow upward current which iscounter to the downwardly penetrating particles will readily carry backor reverse the direction of motion of particles of lesser penetratingpower.

In this manner, the combined alternate action of jet and counter-currenteffectuates a positive separation of small particles of high densityfrom less dense particles of equal or greater volume. The small denseparticles are recovered from the bottom outlet in tank 346 and theremaining less dense particles are removed as tailings, overflowing thetop edge of tank 346.

Thus, in accordance with the present invention, the method of separatingintermixed suspensoids of particles of varying size and differingdensities, basically consists of discharging a stream of a suspension ofsuch intermixed particles at a first relatively high predeterminedvelocity into a fluid body of predetermined density and then imparting amovement to the fluid that is in countercurrent to the movement of theparticles penetrating into the fluid and is of such velocity to overcomethe momentum of low density particles irrespective of their size whilemerely reducing the momentum of the high density particles.

The invention may be embodied in other specific forms without departingfrom the spirit or essential characteristics thereof. The presentembodiments are therefore to be considered in all respects asillustrative and not restric tive, the scope of the invention beingindicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range ofequivalency of the claims are therefore intended to be embraced therein.

What is claimed and desired to be secured by United States LettersPatent is:

l. A method of separating particles of varying size and differingdensities in accord with their densities comprising the steps ofdischarging a stream of a suspension of such particles at a firstpredetermined velocity for penetration into a body of liquid mediumhaving a predetermined density and imparting movement to said body whichis counter to the movement of said stream and which is at a velocitysufiicient to overcome the momentum of the low density particles in thestream irrespective of their size while merely reducing the momentum ofthe high density particles in the stream, said first predeterminedvelocity being imparted to said particles prior to introduction intosaid body.

2. A method of separating particles of varying size and differingdensities in a slurry body comprising the steps of moving said slurrybody in a first direction at a first velocity to impart like velocitiesand differing momenta to said particles proportional in magnitude totheir respective masses, and reversing the direction of movement of thelower density particles therein while merely retarding the rate ofmovement of the higher density particles therein in said first directionby applying a uniform current of viscous resistance to said particlesonly after the like velocities have been imparted to said particle.

3. A method of separating relatively high density fine particles fromrelatively low density particles in a slurry, said method comprising thesteps of providing a confined body of such slurry, providing a memberhaving a horizontally disposed orifice immersed in said slurry body,acting upon said slurry body beneath said member to produce verticalundulant movement of said slurry through the orifice, the upwardmovement of the slurry body being relatively slow and the downwardmovement being relatively rapid, and constricting said orificeimmediately upon initiation of downward slurry movement to a degree toprevent downward movement of the portion of the slurry body above themember at the same rate as the portion thereof beneath said member tothereby create a void between the bottom of said member and top surfaceof said slurry body portion beneath said member and thereby induce theformation of downwardly directed jet discharge stream through theconstricted orifice.

4. The method according to claim 1 comprising the steps of confiningsaid body with at least an intermittent free surface, and emitting saidstream at a predetermined distance from said free surface and in thedirection of 20 said free surface to enable said said body.

5. The method according to claim 4 comprising the steps of alternatingthe counter movement of said body relative to said stream with aconcurrent movement that is in the same direction as the movement ofsaid stream to produce an undulant movement of said body, andmaintaining a predetermined timed relationship between the concurrentand counter current movements of said body and the discharging of saidstream.

6. The method according to claim 5 comprising the step of producing asub-atmospheric space above said free surface by said concurrentmovement of said body to establish a pressure differential for causingemission of said stream.

7. A method of concentrating fine particles of high density from finelyground ore, including the steps of providing a generally horizontallyoriented orificed screen embodying fluid flow responsive means foropening the orifices thereof in response to upward fluid flowtherethrough and for substantially constricting the orifices in responseto downward fiuid flow therethrough, immersing said screen in a confinedbody of slurry, inducing in said slurry below said orificed screensuccessive alternating flows of relatively slow upward movement followedby a relatively accelerated downward movement through the orifices ofthe screen, the rate of downward slurry movement being sufiicientlygreat to induce a vacuum suction space immediately below the screensubstantially simultaneously with the commencement of and responsive tothe rapid downward movement of the slurry and to thereby induce theformation of downwardly directed jets of slurry through the constrictedorifices of the screen and through said space into the body of slurrytherebelow whereby greater kinetic energy and momentum are imparted tofine particles of high density in said downward jets than to theparticles of low density therein, the succeeding slow upward movement ofthe slurry being of such velocity that the lesser downward momentum ofthe particles of relatively lower density is overcome and the lowdensity particles are carried upwardly through the screen open orificesto the upper surface of the slurry for discharge as waste while therelatively higher momentum and kinetic energy of the high densityparticles is merely reduced so that such high density particles continuedownward movement, and drawing off concentrate portions of the slurrybelow the level of the screen.

8. The method for concentrating finely ground mineral particles in aslurry as defined in claim 7, including the steps of fully opening theorifices in the screen substantially immediately upon initiation ofupward slurry movement and maintaining such orifices open during theupward movements of the slurry, and partly closing said orificesresponsive to and substantially simultaneously with the commencement ofthe downward movement of the slurry.

9. Apparatus for concentrating finely ground particles in a slurry,including a tank for containing a slurry therein and having a slurryfeed inlet, a discharge outlet for concentrates at a lower portion ofthe tank and a discharge outlet for waste at an upper portion of thetank, and means operative in said lower portion of the tank forsuccessively pulsating said slurry at a differential of velocityrespectively slowly upwardly and rapidly downwardly, the combinationtherewith of an orificed supporting pocket screen structure mountedtransversely across said tank and dividing the tank into the said upperportion and lower portion said screen structure having spaced apartupper and lower faces and having its area divided into separate pocketsopen at both ends to provide fluid communication through said screen andadapted for separately seatingly receiving and holding a ball therein,the openings of said pockets at said lower face being of relativelysmaller area than the openings at said upper face, at least one of theside walls'of each of said pockets being inclined upparticles topenetrate into 21 wardly and outwardly between the said respective upperand lower openings to permit movement of said balls in said pockets, andmeans overlying the pockets for limiting the upward movement of balls inthe pockets beyond the confines of the pockets.

10. In an apparatus for concentrating finely ground particles in aslurry, including a tank for containing a slurry therein and having aslurry feed inlet, a discharge outlet for concentrates at a lowerportion and a discharge outlet for waste at an upper portion, and meansoperative in said lower portion of the tank for successively pulsatingsaid slurry at a differential of velocity respectively slowly upwardlyand rapidly downwardly, the combination therewith of an orificedsupporting screen structure mounted transversely across said tank anddividing the tank into the said upper portion and lower portion, saidscreen structure having separate pockets open at the top and each formedwith an orifice disposed in the bottom thereof to provide fluidcommunication through said screen structure through which flows ofslurry may be pulsated, a ball shiftably positioned in each pocket,being of a shape and area relative to the size of the balls whereby theballs in the respective pockets are adapted to be seatingly supported bythe edges of said pocket forming said orifices and to maintain a portionof said lower orifices open for passage of slurry therethrough, and aguard grille overlying the pockets in sufiicient proximity thereto forconfining said balls against movement out of pockets by the forceexerted by the upward flow of the slurry.

11. In an apparatus for concentrating finely ground particles in aslurry, including a tank for containing a slurry therein and having aslurry feed inlet, a discharge outlet 'for concentrates at a lowerportion and a discharge outlet for waste at an upper portion, and meansoperative in said lower portion of the tank for successively pulsatingsaid slurry at a differential of velocity respectively slowly upwardlyand rapidly downwardly, the combination therewith of a supporting screenstructure mounted transversely across said tank and dividing the tankinto the said upper portion and lower portion said screen structurehaving a plurality of orifices through which flows of slurry may bepulsated, a plurality of balls associated individually with saidorifices, said orifices being of a shape and area relative to the sizeof the balls whereby the balls associated with the respective orificesmay be supported by the edges of said orifices and maintain a portion ofsaid orifices open for passage of slurry therethrough, and a guardgrille overlying said screen in sufficient proximity thereto forconfining said balls against the upward flow of the slurry.

12. In an apparatus for separating intermixed particles having varyingsize and differing densities in accord with their densities, a vesselconfining a body of slurry having a free unconfined top surface; meansfor projecting at least one stream of a suspension of said intermixedparticles at said free surface of said body of slurry with a sufficientpredetermined first velocity to penetrate said body of slurry includinga member having at least one orifice therein disposed over said freesurfacein fluid communication therewith and supply means for deliveringsaid suspension of intermixed particles to said orifice under apredetermined pressure; and delivery means separate from said supplymeans for introducing a fluid medium to said vessel at a point to causean upward movementof said slurry in counter current to said stream.

13. The apparatus as defined in claim 12 wherein said member is fixedrelative to said vessel.

14. The apparatus as defined in claim 12 wherein means are provided forcontrolling the delivery of said suspension and said medium ininterlocked relationship so that the delivery of said suspension andsaid medium takes place in sequence.

15. The apparatus as defined in claim 12 wherein said supply meanscomprise means defining a pressure chamber with said member and fluidpump means having an outlet 22 in fluid communication with said pressurechamber and operative to establish a pressure differential across saidorifice for producing said stream.

16. In an apparatus for separating intermixed particles suspended in afluid, a tank open at least at its bottom end, a rigid closure memberdisposed beneath the bottom end of said tank, flexible means attachingsaid closure member in liquid tight relationship to said tank so thatsaid closure member is at least vertically displaceable relative to saidtank and encloses the bottom open end thereof, flexible meansresiliently supporting only a predetermined portion of the dead weightof said closure member, and means resiliently supporting the remainderof the Weight of said closure member and the weight of the contents insaid tank comprising motor means having a power member operably movablein opposed directions at difiering predetermined velocities, meansincluding a resilient member operably coupling said closure member withsaid power member for transmitting motion of said power member to saidclosure member to reciprocate said closure member with a slow upwardmovement and a relatively rapid downward movement, said flexible meansand said resilient member cushioning and shocklessly interrupting thedownward movement of said closure member.

17. In an apparatus for separating intermixed particles suspended in afluid, a tank for confining a body of said fluid and open at least atits bottom end, a rigid closure member disposed beneath the bottom endof said tank, flexible means attachingsaid closure member in fluid tightrelationship to said tank so that said closure member is at leastvertically reciprocable to said tank, drive means operably coupled tosaid closure member for imparting alternating and successive slow upwardand rapid downward movement to said closure member, and means forcontrolling the magnitude of velocity at which said closure member ismoved upwardly in response to variations in the density of said fluid.

18. The apparatus as defined in claim 17 wherein said drive meansincludes fluid operated motor means having a pressure fluid inlet,closure member support means operably coup-ling said motor means to saidclosuremember and including a movable member responsive to variations inthe weight of fluid in said tank, valve means in said pressure fluidinlet for controlling the introduction of pressure fluid into said motormeans, and means operatively connecting said movable member to saidvalve means to operate said valve means and control the rate of pressurefluid flow to said motor means in proportion to the changes in densityof said tank.

19. In an apparatus for separating particles suspended in a slurry inaccordance with their densities, a tank for containing a slurry thereinand having a slurry feed inlet, a discharge outlet for concentrates at alower portion and a discharge outlet for waste at an upper portion,movable means operative in said lower portion of the tank for pulsatingsaid slurry, a grid structure mounted transversely across said tank in apredetermined position and dividing the tank into the said upper portionand lower portion, said grid structure having a plurality of orificesproviding fluid communication between the upper and lower portions ofsaid tank, motor means operatively coupled to said movable means forsuccessively and alternately imparting slow upward movement andrelatively rapid downward movement to said movable means whereby theslurry in said tank is alternately moved slowly upwardly through saidorifices and above said grid structure and rapidly downwardly throughsaid orifices and means cooperating with said orifices in said gridstructure and operative by the pulsations imparted to said slurry toallow fluid flow through the entire cross sectional flow area of saidorifices upon upward movement of said slurry but to effectivelypartially reduce the magnitude of the flow area through said orificesupon downward movement of said slurry to thereby temporarily trap aportion of said slurry above said grid structure and to establish a lowpressure void immediately below said grid structure whereby slurry fromabove said grid structure is discharged through the eflectively reducedflow area of said orifices in the form of jet streams of predeterminedvelocity, said orifices being approximately vertically disposed so thatsaid jet streams project toward the free surface of said slurry belowsaid grid structure to penetrate said slurry, said inlet feed beingcentrally disposed above said grid structure and including a feed duct,means defining a feed well centrally above said grid structure andcommunicating with said duct, said discharge outlet for waste beingdisposed above said grid structure about the periphery of said tankwhereby cross currents of slurry between said inlet feed and saiddischarge for waste are minimized.

20. In an apparatus for separating particles suspended in a slurry inaccordance with their densities, :a tank for containing a slurry thereinand having a slurry feed inlet, a discharge outlet for concentrates at alower portion and a discharge outlet for waste at an upper portion,movable means operative in said lower portion of the tank for pulsatingsaid slurry, a grid structure mounted transversely across said tank in apredetermined position and dividing the tank into the said upper portionand lower portion, said grid structure having a plurality of orificesproviding fluid communication between the upper and lower portions ofsaid tank, motor means operatively coupled .to said movable means forsuccessively and alternately imparting slow upward movement andrelatively rapid downward movement to said movable means whereby theslurry in said tank in alternately moved slowly upwardly through saidorifices and above said grid structure and rapidly downwardly throughsaid orifices and means cooperating with said orifices in said gridstructure and operative by the pulsations imparted to said slurry toallow fluid flow through the entire cross sectional flow aera of saidorifices upon upward movement of said slurry but to eifectivelypartially reduce the magnitude of the flow area through said orificesupon downward movement of said slurry to thereby temporarily -trap aportion of said slurry above said grid structure and to establish a lowpressure void immediately below said grid structure whereby slurry fromabove said grid structure is discharged through the effectively reducedflow area of said orifices in the form of jet streams of predeterminedvelocity, said orifices being approximately vertically disposed so thatsaid jet streams project toward the free surface of said slurry belowsaid grid structure to penetrate said slurry, a centrally disposeddischarge being provided to withdraw concentrates collected above saidgrid structure and the upper face of said grid structure being slopeddownwardly toward said discharge from the periphery of said tank toenhance movement of concentrates toward said discharge.

21. In an apparatus for separating particles suspended in a slurry inaccordance with their densities, a tank for containing a slurry thereinand having a slurry feed inlet, a discharge outlet for concentrates at alower portion and a discharge outlet for waste at an upper portion,movable means operative in said lower portion of the tank for pulsatingsaid slurry, a grid structure mounted transversely across said tank in apredetermined position and dividing the tank into the said upper portionand lower portion, said grid structure having a plurality of orificesproviding fluid communication between the upper and lower portions ofsaid tank, motor means operatively coupled to said movable means forsuccessively and al ternately imparting slow upward movement andrelatively rapid downward movement to said movable means whereby theslurry in said tank is alternately moved slowly upwardly through saidorifices and above said grid structure and rapidly downwardly throughsaid orifices and means co-operating with said orifices in said gridstructure and operative by the pulstations imparted to said slurry toallow fluid flow through the entire cross sectional flow area of saidorifices upon upward movement of said slurry but to effectivelypartially reduce the magnitude of the flow area through said orificesupon downward movement of said slurry to thereby temporarily trap aportion of said slurry above said grid structure and to establish a lowpressure void immediately below said grid structure whereby slurry fromabove said grid structure is discharged through the efiectively reducedflow area of said orifices in the form of jet streams of predeterminedvelocity, said orifices being approximately vertically disposed so thatsaid jet streams project toward the free surface of said slurry belowsaid grid structure to penetrate said slurry, said means co-operatingwith said orifices in said grid structure comprising a plurality oforifice closure members associated with said orifices and movablerelative to said grid structure by the pulsations of said slurry, saidorifice closure members being of a shape and size relative to the areaand shape of said orifices so as to be supported by the edges of saidorifices and maintain a portion of said orifices open for passage ofslurry therethrough, a screen like guard grille overlying said gridstructure in sufiicient proximity thereto confining said orifice closuremembers against upward flow but allowing limited free movement of saidorifice closure members to permit fluid flow substantially through theentire flow area of said orifices, a centrally disposed dis charge beingprovided to withdraw concentrates collected above said guard grille andsaid guard grille being sloped downwardly toward said discharge from theperiphery of said tank to enhance movement of concentrates toward saiddischarge.

22. In an apparatus for separating particles suspended in a slurry inaccordance with their densities, a tank for containing a slurry thereinand having a slurry feed inlet, a discharge outlet for concentrates at alower portion and a discharge outlet for Waste at an upper portion,movable means operative in said lower portion of the tank for pulsatingsaid slurry, a grid structure mounted transversely across said tank in apredetermined position and dividing the tank into the said upper portionand lower portion, said grid structure having a plurality of orificesproviding fluid communication between the upper and lower portions ofsaid tank, motor means operatively coupled to said movable means forsuccessively and alternately imparting slow upward movement andrelatively rapid downward movement to said movable means whereby theslurry in said tank is alternately moved slowly upwardly through saidorifices and above said grid structure and rapidly downwardly throughsaid orifices and means co-operating with said orifices in said gridstructure and operative by the pulsations imparted to said slurry toallow fluid flow through the entire cross sectional flow area of saidorifices upon upward movement of said slurry but to effectivelypartially reduce the magnitude of the flow area through said orificesupon downward movement of said slurry to thereby temporarily trap aportion of said slurry above said grid structure and to establish a lowpressure void immediately below said grid structure whereby slurry fromabove said grid structure is discharged through the effectively reducedflow area of said orifices in the form of jet streams of predeterminedvelocity, said orifices being approximately vertically disposed so thatsaid jet streams project toward the free surface of said slurry belowsaid grid structure to penetrate said slurry, said means cooperatingwith said orifices in said grid structure comprising a plurality oforifice closure members associated with said orifices and movablerelative to said grid structure by the pulsations of said slurry, saidorifice closure members being of a shape and size relative to the areaand shape of said orifices so as to be supported by the edges of saidorifices and maintain a portion of said orifices open for passage ofslurry therethrough, a screen like guard grille overlying said gridstructure in sufiicient proximity thereto confining said orifice closuremembers against upward'flow but allowing limited free movement of saidorifice closure members to permit fluid flow substantially through theentire flow area of said orifices, a layer of particles havingindividual densities substantially greater than the density of saidslurry being disposed over said guard grille.

23. The apparatus as defined in claim 22 wherein a layer of coarsebedding material is disposed over the top of said layer of particles,the density of said bedding material having a density approximatelyequal to the minerals to be recovered from said slurry.

24. In an apparatus for separating particles suspended in a slurry inaccordance with their densities, a tank for containing a slurry thereinand having a slurry feed inlet, a discharge outlet for concentrates at alower portion and a discharge outlet for waste at an upper portion,movable means operative in said lower portion of the tank for pulsatingsaid slurry, a grid structure mounted transversely across said tank in apredetermined position and dividing the tank into the said upper portionand lower portion, said grid structure having a plurality of orificesproviding fluid communication between the upper and lower portions ofsaid tank, motor means operatively coupled to said movable means forsuccessively and alternately imparting slow upward movement andrelatively rapid downward movement to said movable means whereby theslurry in said tank is alternately moved slowly upwardly through saidorifices and above said grid structure and rapidly downwardly throughsaid orifices and means co-operating with said orifices in said gridstructure and operative by the pulsations imparted to said slurry toallow fluid flow through the entire cross sectional flow area of saidorifices upon upward movement of said slurry but to effectivelypartially reduce the magnitude of the flow area through said orificesupon downward movement of said slurry to thereby temporarily trap aportion of said slurry above said grid structure and to establish a lowpressure void immediately below said grid structure whereby slurry fromabove said grid structure is discharged through the eiiectively reducedflow area of said orifices in the form of jet streams of predeterminedvelocity, said orifices being approximately vertically disposed so thatsaid jet streams project toward the free surface of said slurry belowsaid grid structure to penetrate said slurry, and means for introducingmedia of selected density into said tank comprising a duct adapted to beconnected to a source of media and extending into the interior formed bysaid tank and said movable means and terminating in an outlet below saidgrid structure, and a perforated hood disposed over said outlet touniformly distribute liquid introduced through said duct into said tank.

25. The apparatus as defined in claim 23 wherein means are provided forremoving of sands accumulating on top of said bedding comprising meansforming an opening in the side of said tank above sand bedding and aplate structure having closed sides and an inclined portion extendingdownward from said tank from above said opening between said sides andterminating a predetermined height above said bedding.

26. Apparatus for concentrating finely ground particles in a slurry,including a tank for containing a slurry therein and having a slurryfeed inlet, a discharge outlet for concentrates at a lower portion ofthe tank and a discharge outlet for waste at an upper portion of thetank, and means operative in said lower portion of the tank forsuccessively pulsating said slurry at a difierential of velocityrespectively slowly upwardly and rapidly downwardly, the combinationtherewith of a planar orificed supporting pocket screen mountedlaterally transversely across said tank and dividing the tank into thesa d upper portion and lower portion, said screen comprising a planarbody having an upper face and a lower face which are relatively spacedby the planar body, said screen body having its planar area divided intoseparate pockets each adapted for separately receiving and holdmg a balltherein, the said separate pockets being open at said upper face andhaving an opening at said lower face of relatively smaller area than theupper opening, the side walls of said pockets being inclined upwardlyand outwardly between the said respective upper and lower openings, andmeans overlying the pockets for limiting the upward movement of balls inthe pockets beyond the confines of the pockets.

2 7. In apparatus for concentrating finely ground particles in a slurry,including a tank for containing a slurry therein and having a slurryfeed inlet, a discharge outlet for concentrates at a lower portion and adischarge outlet for waste at an upper portion, and means operative insaid lower portion of the tank for successively pulsating said slurry ata differential of velocity respectively slowly upwardly and rapidlydownwardly, the combination therewith of a planar orificed supportingscreen mounted laterally transversely across said tank and dividing thetank into the said upper portion and lower portions, said screen havingseparate pockets each provided with an orifice through which flows ofslurry may be pulsated, a separate ball in each pocket, the said pocketsbeing open at the upper planar portion and having the orifices thereofat a lower planar portion, said lower orifices of the pockets being of ashape and area relative to the size of the balls whereby the balls inthe respective pockets may be supported by the edges of said lowerpocket orifices and maintain a portion of said lower orifices open forpassage of slurry therethrough, and a guard grille overlying the pocketsin sufficient proximity thereto for confining balls in said pocketsagainst the upward flow of the slurry.

References Cited in the file of this patent UNITED STATES PATENTS1,078,520 Stromberg Nov. 11, 1913 2,138,810 Wood NOV. 29, 1938 2,199,091Pardee Apr. 30, 1940 2,242,020 Wood May 13, 1941 2,271,650 Kraut Feb. 3,1942 2,416,066 Phelps Feb. 18, 1947 2,708,517 Evans May 17, 1955

12. IN AN APPARATUS FOR SEPARATING INTERMIXED PARTICLES HAVING VARYING SIZE AND DIFFERING DENSITIES IN ACCORD WITH THIER DENSITITES, A VESSEL CONFINING A BODY OF SLURRY HAVING A FREE UNCONFINED TOP SURFACE; MEANS FOR PROJECTING AT LEAST ONE STREAM OF A SUSPENSION OF SAID INTERMIXED PARTICLES AT SAID FREE SURFACE OF SAID BODY OF SLURRY WITH A SUFFICIENT PREDETERMINED FIRST VELOCITY TO PENETRATE SAID BODY OF SLURRY INCLUDING A MEMBER HAVING AT LEAST ONE ORIFICE THEREIN DISPOSED OVER SAID FREE SURFACE IN FLUID COMMUNICATION THEREWITH AND SUPPLY MEANS FOR DELIVERING SAID SUSPENSION OF INTERMIXED PARTICLES TO SAID ORIFICE UNDER A PREDETERMINED PRESSURE; AND DELIVERY MEANS SEPARATE FROM SAID SUPPLY MEANS FOR INTRODUCING A FLUID MEDIUM TO SAID VESSEL AT A POINT TO CAUSE AN UPWARD MOVEMENT OF SAID SLURRY IN COUNTER CURRENT TO SAID STREAM. 